This invention relates to the control of fluids using solenoid-actuated valves.
Solenoid-actuated valves operate by supplying a known quantity of current through a solenoid that generates a magnetic field. The magnetic field attracts a movable internal element of the valve that selectively blocks or unblocks the flow of fluid through the valve. These valves are intended to operate accurately and efficiently to produce a controlled fluid flow between two or more fluid flow passages.
Conventional valve designs typically have a spring for one valve seat, typically normally open, sufficient in force to seal against a required pressure, and a second spring for the opposite valve seat, typically normally closed, sufficient in force to both seal against a required pressure and to overcome the force of the opposite (normally open) spring. Typically, the normally closed spring must provide more force than the normally open spring. This requires stronger and perhaps heavier springs, as well as a larger solenoid to overcome the force of the larger normally closed spring.
Typical valves that employ internal springs also have one or both springs located in the path of fluid flow, therefore the media that the valve controls can act to wear or corrode the springs. Other valves generally isolate the springs from the active flow path with a diaphragm or protective barrier.
There are many applications for fluid control valves in for example, the medical, chemical and semiconductor industries, such as, in chemical analysis, filtration, pumping systems, and gas delivery equipment. The cost associated with each cubic meter of building space has made it highly advantageous to reduce the size of the equipment employed in these industries.